docs: def score(self, eval_instances, verbosity=0):
          '''
          Return scores (negative log likelihoods) assigned to each testing
          instance in `eval_instances`.
  
          :param eval_instances: The data to use to evaluate the model.
              Instances should have at least the `input` and `output` fields
              populated. `output` is needed to define which score is to
              be returned.
          :param verbosity: The level of diagnostic output, relative to the
              global --verbosity option. Used to adjust output when models
              are composed of multiple sub-models.
          :type eval_instances: list(instance.Instance)
  
          :returns: list(float)
          '''
          if hasattr(self, '_using_default_combined') and self._using_default_combined:
              raise NotImplementedError
  
          self._using_default_separate = True
          return self.predict_and_score(eval_instances, verbosity=verbosity)[1]